题解 | #链表的奇偶重排#

<?php

/*class ListNode{
    var $val;
    var $next = NULL;
    function __construct($x){
        $this->val = $x;
    }
}*/

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @return ListNode类
 */
function oddEvenList( $head )
{
    // write code here
    if($head==null || $head->next==null){
        return $head;
    }
    $odd = $head;
    $even = $head->next;
    $evenHead = $even;
    while($even && $even->next){
        $odd->next = $even->next;
        $odd = $even->next;
        $even->next = $odd->next;
        $even = $odd->next;
    }
    $odd->next = $evenHead;
    return $head;
}